Final Answer:
The standard enthalpy change (ΔHrxn) for the given reaction is -1075 kJ/mol.
Step-by-step explanation:
The enthalpy change of a reaction, represented by ΔHrxn, is the heat energy released or absorbed during a chemical reaction at constant pressure. In this case, we are considering the reaction: 2 OF2 (g) + 2 S (s) → SO2 (g) + SF4 (g). The coefficients in the balanced equation indicate the stoichiometry of the reaction. To calculate ΔHrxn, we subtract the sum of the standard enthalpies of the reactants from the sum of the standard enthalpies of the products.
Firstly, we need to look up the standard enthalpy values for each substance involved in the reaction. The standard enthalpy of formation (ΔHf°) for OF2 is 0 kJ/mol, for S (s) is 0 kJ/mol, for SO2 (g) is -296.8 kJ/mol, and for SF4 (g) is -948.2 kJ/mol. Applying Hess's Law, the equation becomes: ΔHrxn = ΣΔHf°(products) - ΣΔHf°(reactants). Plugging in the values, we get ΔHrxn = [(-948.2 kJ/mol) + (-296.8 kJ/mol)] - [2(0 kJ/mol) + 2(0 kJ/mol)] = -1075 kJ/mol.
The negative sign indicates that the reaction is exothermic, meaning it releases heat to the surroundings. In this context, the system loses energy, and the surroundings gain energy. The calculated value of -1075 kJ/mol represents the standard enthalpy change for the given chemical reaction under standard conditions.